1. Field of the Invention
The present invention relates to an endoscope in which various kinds of units are fixed to a distal end portion of an insertion portion.
2. Description of the Related Art
As is commonly known, endoscopes are widely used for observation, treatment and the like of an inside of a living body (an inside of a body cavity) or inspection, repair and the like of an inside of industrial plant facilities.
In such an endoscope, an image pickup unit in which an objective optical system is arranged, an illumination unit in which an illumination optical system is arranged, a channel unit for a treatment instrument channel, a nozzle unit for air/water feeding and the like are fixed to a distal end portion with screw members.
The various kinds of units are fixed by screwing screws into screw holes tapped in a distal end portion body, which is a distal end member provided on the distal end portion of the endoscope, and, furthermore, bonded and fixed so that the screws are not loosened.
Furthermore, recently, downsizing of the distal end portion has been promoted, accompanying diameter reduction for the insertion portion of the endoscope, and use of resin for the distal end portion body has been promoted from demands for complicated shape forming, integration, weight reduction and the like of the distal end portion.
When the distal end portion body is formed with resin as described above, there may be a case where the screw holes of a distal end rigid portion made of the resin are shaven and damaged by the screw members of fixing members for fixing the various kinds of units being screwed and removed at time of performing repair, maintenance and the like for the various units. When the screw holes of the distal end portion body are damaged, necessity for exchanging the distal end portion body of the endoscope occurs.
In order to prevent this, for example, Japanese Patent Application Laid-Open Publication No. 2013-128710 discloses a technique for an endoscope parts fixing structure which prevents fixed members from being damaged by fitting and removing fixing members.
In the conventional endoscope parts fixing structure, recess portions at a positions facing and overlapping with hole portions of a distal end portion body are formed on various kinds of units to be fitted to the distal end portion body on which the hole portions are formed, for example, an image pickup unit here; a projection portion to be engageably inserted into the recess portion of the image pickup unit is provided on a fixing member to be inserted into the hole portion of the distal end portion body; and, by rotating the fixing member so that the projection portion of the fixing member is shaved or deformed by wall surfaces forming the recess portion of the image pickup unit to be flattened, the image pickup unit is fixed to the distal end rigid portion.